I feel like this year so many events have had their own hashtag to define them that I'll nominate

Hashtag

Events having hashtags of their own is not new for 2012. Afterall, #eqnz was a nominee in both 2010 and 2011. What is new for 2012 is "hashtag" becoming a word in its own right. People talk about hashtags without needing to gloss what it means. And check out the IRL spoken use of such lol phrases as "hashtag woteva". And then there's the news that a new parent had (maybe) named their child hashtag. Yeah, the word has become its own thing in 2012. #hashtag